This application is based on Japanese Patent Application No. 251632/1997 filed on Sep. 17, 1997, No. 251633/1997 filed on Sep. 17, 1997, and No. 251634/1997 filed on Sep. 17, 1997, the contents of which are incorporated herein by reference.
1. Field of the Invention
This invention relates to a method of printing and a printing system for printing an image on the basis of an image data contained in an image file. The image file is specified by a user and transmitted from his or her data processor to a printer through a telecommunication line.
2. Description of the Prior Art
With an increase in image software and with the spread of communication between personal computers, it is becoming possible for the user of a personal computer to allow any kind of images to be displayed on the screen of his or her personal computer. The availability of high-performance printers which are relatively inexpensive in cost makes it easy to print the images.
Some of the high-performance printers are capable of printing out color images in large-sized copy with picture quality approximating to that of silver photography. However, it should be realized that it would be expensive for a common user to personally possess such an extra-high-performance printer.
A printing system for solving the aforesaid problem has heretofore been proposed (as disclosed in Japanese Laid Open Patent Application No. 9-39311), where a plurality of personal computers are connected to an extra-high-performance color printer by means of a telecommunication line so that the color printer may be put to common use by the users of the personal computers.
FIG. 20 depicts a conventional printing system 800 comprising personal computers 802a to 802c, high-performance color printer 804, printer controller 805 for controlling the color printer 804, display 803 attached to the printer controller 805, and telecommunication line 806. The personal computers 802a to 802c are provided at the residences of users, while the color printer 804 and the printer controller 805 are installed, e.g., in a convenience store.
Let it be assumed that the user of the personal computer 802a wishes to print out an image. He or she inputs an image file DFa, an instruction for giving advance notice of printing, and his or her name.
The personal computer 802a gives an image file number 903a to the image file DFa and transmits a headder file 902a, which consists of the user's name and the image file number 903a, to the printer controller 805 and the color printer 804, in both of which headder files 902a to 902c transmitted from the personal computers 802a to 802c are stored. At this point of time, the image file DFa per se has not been transmitted to the printer controller 805 and the color printer 804 as yet.
The user of the personal computer 802a goes to the convenience store in which the printer controller 805 and the color printer 804 are installed, because he or she has to give to them a command to execute a printing process. He or she finds out his or her name and image file number 903a from among a plurality of users' names and image file numbers 903a to 903c displayed on the screen of the display 803 attached to the printer controller 805, and inputs an instruction for causing the color printer 804 to execute the printing process for the image file number 903a. Then the image file DFa is transmitted from the personal computer 802a to the color printer 804 and stored in a memory 807 incorporated therein. Thereafter, the printing process is executed.
Because of a plurality of users' names and,image file numbers 903a to 903c displayed on the screen of the display 803, it is difficult to preclude the possibility of a wrong image file number being chosen by mistake.
A further previously proposed printing system (see Japanese Laid Open Patent Application No. 7-14326) has been designed such that an image file transmitted from a client to a server is erased when a request for the image file is not made from a printer within a prescribed length of time.
A particular advantage obtained from this printing system resides in the fact that the necessity of storing a large number of image files, for which printing processes are not executed, is avoided.
On the other hand, one of the problems encountered with this printing system is that an image file, for which the execution of a printing process is necessary but has been delayed for some reason or other, is also erased.
In order to cope with the aforesaid problem, information on whether consent to the erasion is given or withheld may be regarded as suitable for being added to an image file when it is transmitted from a client to a server. The use of such information is, however, undesirable because many users will aimlessly withhold their consent to the erasion. The result is that a large number of image files will have to be stored in a memory.
The conventional printing system 800 shown in FIG. 20 has another disadvantage which is derived from the fact that the image file DFa is not transmitted from a personal computer to the color printer 804 until the user of the personal computer inputs an instruction for causing the color printer 804 to execute the printing process. This means that execution has to be suspended while waiting for the image file DFa from the personal computer.
As is known, the capacity of an image file and the time required for transmitting it from a personal computer to the color printer 804 are proportional to the size and the desired picture quality of an image. Long waiting time comes to nothing and adversely affects the productive capacity of the color printer 804.
As an alternative to the foregoing, all the image files DFa for which it may possibly be found desirable to execute printing processes in the future may be transmitted beforehand from the personal computer 802a to the color printer 804. This alternative is, however, undesirable because it requires a large-capacity memory to be incorporated in the color printer 804 for storing a large number of image files DFa and will thereby result in high costs.